1. Field of the Invention
Embodiments of the invention relate to a solar cell and method for manufacturing the same.
2. Discussion of the Related Art
Recently, as exhaustion of existing energy resources such as oil or coal is foreseen, interest in alternative energy to replace them is increasing and a solar cell that produces electric energy from solar energy is receiving much attention.
A solar cell is classified into a crystalline solar cell, an amorphous solar cell, a compound-based solar cell, and the like, depending on the kinds of materials used for the solar cell. Further, a crystalline silicon solar cell is classified into a mono-crystalline (or single crystalline) silicon solar cell and a polycrystalline silicon solar cell.
The monocrystalline silicon solar cell, having a high quality substrate, can easily accomplish as high an efficiency, but it is disadvantageous in that a great amount of fabrication cost is incurred. In comparison, the polycrystalline silicon solar cell is disadvantageous in that it cannot accomplish high efficiency because its substrate is inferior to that of the mono-crystalline silicon solar cell, but recently, the substrate quality of the polycrystalline silicon solar cell has been improved and, as processing techniques of the polycrystalline silicon solar cell are advancing, the polycrystalline silicon solar cell is becoming highly efficient.
One of methods for making the polycrystalline silicon solar cell highly efficient is by reducing reflectivity of light that is incident to a light reception surface of a substrate.
In order to reduce light reflectivity, the light reception surface of the substrate is formed to have protrusions and depressions. Namely, the substrate is formed to have a textured surface.
However, the solar cell having such a structure has a doubled surface area due to the protrusions and depression formed on the textured surface, so that a recombination rate at the surface increases. Thus, the lowering of the reflectivity brings about the increase in carriers, but because some of the carriers become extinct due to their recombination, an actual current gain is not increased as much as the increase in the carriers.